In recent years, it has become clear that molecular events leading to oncogenesis include not only genetic mutations, but also epigenetic alterations, such as the DNA methylation of promoter CpG islands. We have shown that DNA methylation changes are both causal contributors to neoplasia, and potential biomarkers for cancer, including adenocarcinoma of the esophagus. We have developed a sensitive, quantitatively accurate, automated DNA methylation analysis technique, called MethyLight, with which we have shown that DNA methylation profiles can discriminate between normal squamous mucosa of the esophagus, intestinal metaplasia, and dysplasia. These preliminary results suggest that DNA methylation markers could eventually be exploited as clinical tools in the early detection of esophageal adenocarcinoma and/or in risk assessment in surveillance programs. Since the 1970s, incidence rates for esophageal and gastric cardia adenocarcinomas have risen substantially, particularly among white males in the United States. Reasons for the increase of these tumor types are not well understood. We have conducted a case-control study to determine the role of smoking, alcohol use, body size characteristics, and other risk factors in the etiology of adenocarcinoma of the esophagus and gastric cardia. Here we propose to use automated MethyLight technology to generate extensive methylation profiles for tissue samples retrieved from this population-based case-control study. This will allow us to identify superior methylation markers for further development and testing as clinical tools in the early detection of esophageal adenocarcinoma, and for the differentiation of Barrett's cases that are at high risk for further progression. We will also investigate whether factors known to increase the risk of adenocarcinoma of the esophagus, increase the risk of DNA methylation in normal tissue, or in the resulting adenocarcinoma.